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  1. #1

    drain line heater for walk in?

    O.K. this might sound like a stupid question but I have to ask. I've only worked on a hand ful of walk in freezers, and i guess i never paid much attention to the drain lines before. A friend showed me his walk in with overflowed frozen drain pan and losts of ice on the floor below. obvious drainage issues. Than I see the black drain line heater wraped around the outside of a 3/4 PVC drain that makes an easy short run straight out the back.
    my questions are, the drain line heater is supposed to go inside the drain line right? and is that ok to put it inside of a PVC drain line or should I make a copper one? Third, is the drain heater supposed to be hot all the time or just in defrost? what about drain pan heaters, are those hot all the time or just in defrost?

    It's a Larkin evap farley new in good shape, I didn't see the defrost timer any where outside, is it possible that it's on the side of the evap with all the other electricals?

    Any thoughts or something I'm not seeing please feel free.

  2. #2
    Join Date
    Dec 2008
    Posts
    12
    Typically the wrap is wound around the outside of the PVC or copper drain pipe. It can be hard wired into the defrost timer so that it runs all the time except in defrost, or you could run the tape to a receptacle mounted on the box so that it uns all of the time.

    How is the pitch on the drain? For a W.I. Freezer I like to see a strong pitch of around 4" per foot. Also insulate the drain with armaflex.

    You want to have as short of a drain run as possible inside the freezer. Make sure to trap the drain on the outside of the box.

    It is possible that the Defrost Time Clock is mounted in the panel with the other controls.

  3. #3
    Join Date
    Aug 2007
    Posts
    245

    Stupid Question??

    Quote Originally Posted by swinginutters View Post
    O.K. this might sound like a stupid question but I have to ask. I've only worked on a hand ful of walk in freezers, and i guess i never paid much attention to the drain lines before. A friend showed me his walk in with overflowed frozen drain pan and losts of ice on the floor below. obvious drainage issues. Than I see the black drain line heater wraped around the outside of a 3/4 PVC drain that makes an easy short run straight out the back.
    my questions are, the drain line heater is supposed to go inside the drain line right? and is that ok to put it inside of a PVC drain line or should I make a copper one? Third, is the drain heater supposed to be hot all the time or just in defrost? what about drain pan heaters, are those hot all the time or just in defrost?

    It's a Larkin evap farley new in good shape, I didn't see the defrost timer any where outside, is it possible that it's on the side of the evap with all the other electricals?

    Any thoughts or something I'm not seeing please feel free.
    There is no such thing as a stupid question on this site......you have posted a good question and will get the best answers from the best guys on this site.

  4. #4
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    1,331
    Most walk-in-freezer drain lines that I've seen have the heat cable on the outside of the pipe. Get rid of that PVC pipe. The plastic is an insulator and will prevent the heat cable from doing it's job very well, besides, the pipe is probably cracked and broken by now anyways. I don't like to see PVC pipe used in coolers either because I believe they clog up easier than copper. What I usually do is run the drain in 3/4" I.D. copper with plenty of pitch, run the heat cable along the bottom of the pipe, tape the heat cable onto the pipe with aluminum tape every foot or so to keep the cable in good contact with the pipe, and then cover the entire thing in Armaflex insulation. They should be powered up all of the time. The condensate pan heater is usually powered through the time clock to turn on and off at the same time as the defrost heaters.

    It is possible that the defrost clock could be anywere the electrican decided to put it. Sometimes they are hidden above the celing, sometimes they are in the condensing unit, sometimes they are in the freezer behind the evaporator. Good luck.

  5. #5
    good info thanks, the drain has good fall to it probably about 6 inches a foot. and I trust you when you say to make sure it has a trap, but just curious why, cause it shouldn't be pulling air through like an A/C should it?

  6. #6
    Join Date
    Jul 2005
    Location
    FLORIDA
    Posts
    1,163
    your heat tape needs to keep the pipe above 32 Degrees for condensate not to freeze and not put anymore load than nessesary on the freezer

    i have found that most times that stacking under the evap coil knocks out the plug and splits the drain line for a mojor pain(and mess) of a repair by the time you get the call
    once you think you've seen it all
    (THINK AGAIN)
    I would rather work for free than be look upon as a thief!!!!!

  7. #7
    Join Date
    Jun 2006
    Location
    New Jersey
    Posts
    4,340
    Quote Originally Posted by swinginutters View Post
    good info thanks, the drain has good fall to it probably about 6 inches a foot. and I trust you when you say to make sure it has a trap, but just curious why, cause it shouldn't be pulling air through like an A/C should it?
    Most evaps are pull throughs. So yes the condensate in on the negative side of the fans. Needs a trap.

  8. #8
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,893
    Quote Originally Posted by ascj View Post
    Most evaps are pull throughs. So yes the condensate in on the negative side of the fans. Needs a trap.
    But during defrost, when water is actually draining the fans aren't running. So no negative pressure.

  9. #9
    Join Date
    Feb 2007
    Location
    Northern NJ
    Posts
    656
    it needs a trap. without it, it will pull moist air from whereever the drain line terminates. just make sure not to trap it in the freezer. you want the water out of there as quickly as possible.

  10. #10
    Join Date
    Aug 2007
    Location
    Winter Haven, FL
    Posts
    4,380
    You can put the trap on the outside of box to make it easy to apply the heat tape.

  11. #11
    Join Date
    Oct 2008
    Location
    Canada
    Posts
    83
    It's mostly been said but,
    1) Heat trace should be coiling around the outside of the drain line, use electrical tape at elbows and unions to ensure it doesn't touch itself (it can burn out if it's touching) and it never hurts to armaflex over it, i've been told it's not necessary but I've always done it.
    2) If possible it should be wired to (1) and (N) from the time clock, ensuring power all the time, assuming 208/230V heat tape.
    3) Drain should be copper, also should be sloped (sounds like you have a good one) as much as possible and should never have a trap in the freezer, but must have a trap. This ensures no air is sucked into the box.
    4) Condensate drain pan should be wired to (3) and (N) from the time clock with the coil heaters, to run in defrost only, as with a proper drain there shouldn't be anything in the drain pan unless the coil is defrosting.
    *Check your wiring diagram as the above mentioned terminals relate to many, but not all t/c's and evaps.

  12. #12
    Join Date
    Oct 2008
    Location
    Canada
    Posts
    83
    Quote Originally Posted by kbghdg View Post
    But during defrost, when water is actually draining the fans aren't running. So no negative pressure.
    yes, but after defrost without trap... Fans running, empty drain line...

  13. #13
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    I use to sub for a manufacturer doing their walkins, and they came up with a pretty good idea on drains. Electrical gray PVC, with heater cable inserted inside the entire length. Just small walk ins, nothing bigger than 1000 sqft. I took one look at this and said there was no way I was gonna run freezer drains this way. Well, after looking at some installations and seeing that even after 2 years there was no problems, and how clean it looked, I was convinced.

    And if a heater does fail and the pipe needs to be repaired it's much easier. I will tell you what, it's a smart clean cheap efficient method for smaller walk ins.

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